From: Tim K. <tim...@ce...> - 2009-07-23 15:05:50
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Dear Roy, On Wed, 22 Jul 2009, Roy Stogner wrote: >> Conclusion: New PetscVector implementation speeds up ghosted vectors >> considerably, while leaving non-ghosted vectors approximately unchanged. >> If the new PetscVector implementation is enabled, the ghosted vectors on >> equal number of cores are approximately equally fast as the non-ghosted >> vectors. If memory is the limitation, ghosted vectors will allow more cores >> per processor and therewith speed up the computation considerably. One of the runtimes I reported last time was actually wrong; here is the corrected table. The change is in line 4. The conclusions stated above remain essentially true, but the new PetscVector implementation indeed also speeds up the non-ghosted vector application. PetVec ghost #cores #nodes hh:mm:ss ---------------------------------------- new ghost 18 3 07:02:54 new ghost 9 3 08:19:55 new no 9 3 08:35:28 old no 9 3 08:57:34 old ghost 9 3 09:36:12 old ghost 18 3 07:30:14 >> Are there any more tests you would like me to perform? > > Presuming you verified correctness too on those runs, Yes, I did. They coincide up to numerical differences. Actually, the largest difference is between 9 cores and 18 cores (of course, because the solver behaves different then). > there's nothing else I can think of. Unless another developer > objects, I'd say we should switch to your new implementation and > turn on ghosted vectors by default. Great! > Would you send me a new patch against the SVN head? I'd hate to dig > through my email for the last patch and then accidentally get the > wrong version. Sure, here you are. Best Regards, Tim -- Dr. Tim Kroeger tim...@me... Phone +49-421-218-7710 tim...@ce... Fax +49-421-218-4236 Fraunhofer MEVIS, Institute for Medical Image Computing Universitaetsallee 29, 28359 Bremen, Germany |